Response of antioxidant systems to copper in the gills of the clam Ruditapes decussatus

Copper (Cu) is an essential element for biological systems, however, when present in excess, is toxic. Metallothioneins can play an important role in Cu homeostasis and detoxification. Moreover, Cu can catalyse the production of toxic hydroxyl radicals that cause lipid peroxidation but defence systems in the cells can limit the oxidative damage. The present study was performed to investigate the effect of three Cu concentrations (0.5, 2.5 and 25 microg l(-1)) on the response of antioxidant enzyme activities (superoxide dismutase (SOD), catalase (CAT), selenium-dependent glutathion peroxidase and total glutathion peroxidase), total proteins, metallothioneins (MT), malondialdehyde (MDA) concentrations in the gills of the clam, Ruditapes decussatus. The activity of antioxidant enzymes and total proteins, MT and MDA concentrations were measured in the gills of the clams after 1, 3, 7, 14, 21 and 28 days of Cu exposure. Results indicate that Cu only induces an imbalance in the oxygen metabolism during the first week of Cu exposure due to a decrease in mitochondrial SOD and CAT, selenium-dependent and total glutathion peroxidase activities. Cu also causes lipid peroxidation, measured by the MDA formation, that was Cu dependent. In the gills of clams exposed to 25 microg Cu/l, the excess of Cu triggers the induction of MT synthesis after 3 days of exposure.     

南海红树林内生真菌1356~#代谢产物的研究

从南海红树林内生真菌1356#分离出两种鞘胺醇(A,B)和三种环二肽(C,D,E)?它们的结构通过IR,MS,1D NMR和2D NMR谱推导出来?(3＇E,4E)-1-(-D-吡喃葡萄糖基-3-羟基-2-(2＇-羟基十八碳酰基)氨基-10-甲基-3＇,4,9-十八碳三烯(A)是一种新的鞘胺醇甙?     

Phenomena caused by seismic and geocryological processes across linear infrastructure, South Yakutia, Russia

High seismic activity, difficult permafrost and hydrogeological conditions of South Yakutia (Russia) complicate building and exploitation of engineering construction and require additional detailed and complex research. These conditions are evident within two sites. The first site is located in the middle reach of the Duray River, where it is crossed by the highway Lena. The second site is located on the right side of the Chulmakan River Valley, 400 meters to the east of the ESPO oil pipeline route. Seismic events, occurring four years ago, led to landslides in the mentioned sites. Formation of joint fissures on slopes assisted drainage of aquifers of free water exchange zone. It is worth noting that at the Duray River site, 59 cm of active soil slumping movement towards the roadbed has occurred within two summer months. Such a process is complicated by cryogenic disintegration of rocks in the base of the landslide body due to groundwater discharge and icing formation in winter.     

Small-area population estimates: a review of methods used in Britain in the 1990s

"Population estimates are usually produced by local government administrations in Britain, for each small area within their authority. Increasing interest has been shown by commerce and by central government. Five main methods are identified: apportionment, ratio change, additive change, cohort survival, and local censuses. Estimation strategies also vary according to available data, the detail in which a population is estimated, and the precise combination of elements chosen from one or more of the main methods. The use of methods at the beginning of the 1990s is surveyed in this paper, and examples given. The accuracy of each main method is quantified from empirical data collated by the Estimating with Confidence project. Likely developments towards the end of the 1990s are reviewed."     

The selection of internal migration models for European regions

"A full multiregional projection model requires migration data that are simultaneously classified by age and gender and region of origin and region of destination. Except for a very small number of regions, these data requirements are so high that aggregation of the data (which is equivalent to simplification of the model) is called for. This paper investigates the extent to which the full internal migration matrix can be simplified without seriously affecting the performance of the resulting multiregional model. Using IPF (iterative proportional fitting) methods, a log-linear analysis of alternative model specifications is made, using data for Italy, the Netherlands and the UK....A reasonable balance between goodness-of-fit and parsimony is found for the model in which time interacts with the main effects only (i.e. with age/sex, with origin and with destination)."     

古巴蛇绿岩侵位

根据岩性和构造特征，古巴划分出三套含蛇绿岩的构造单元：1）北部蛇绿岩带，混杂岩复合体沿古巴岛延伸长度超过1000km；2）白垩纪火山弧建造的变质岩基底；3）中古巴南部Escambray（Guamuhaya）高压变质地块中的构造片体。现有年龄分析资料表明，古巴现存洋壳年代为晚中生代，形成于两种不同的构造背景；1）晚侏罗世-纽康曼期，北美大陆及其南部大陆的漂移造成的小盆地；2）北美被动大陆边缘与阿普第-阿尔必（Aptian—Albian）期火山弧之间形成的俯冲带上部（suprasubduction）边缘盆地。Escambary（Cuamuhaya）地块中生代变质沉积岩中的蛇纹岩片体和高压角闪石形成于一小型洋盆关闭期间．时代很可能为阿尔必（Albian）期。火山弧岩层的变质岩基底来自于上侏罗统-纽康曼阶洋壳，并在中自垩世火山弧形成期间发生变质。北部蛇绿岩带可能来自上述小盆地，以及俯冲边缘盆地的，并自晚白垩世坎佩尼（Campanian）期至始新世中期发生多次侵位。古巴不同的蛇绿岩类型代表了南北美大陆之间泛古陆解体后形成的洋壳的残余物（加勒比洋盆原型）。文章提出并讨论了一种可能的板块构造模型。     

Biomarkers for endocrine disruptors in three species of Mediterranean large pelagic fish

The hypothesis that Mediterranean top predator species, such as large pelagic fish, are potentially at risk due to endocrine disrupting chemicals (EDCs), is investigated. The potential estrogenic effects of PHAHs in three fish species of commercial interest, the top predators bluefin tuna (Thunnus thynnus thynnus), swordfish (Xiphias gladius), and Mediterranean spearfish (Tetrapturus belone), were investigated using vitellogenin (Vtg), zona radiata proteins (Zrp) and mixed function oxidases (EROD, BPMO) as diagnostic tools. High induction of Vtg and Zrp was detected by western blot and ELISA techniques in adult males of X. gladius and T. thynnus thynnus, suggesting that these species are at high toxicological risk in the Mediterranean sea. Comparison of BPMO and EROD activities in the three species indicated, both in male and female, much higher MFO activity in bluefin tuna. This data suggests high exposure of this species to lipophilic xenobiotic contaminants in the Mediterranean environment.     

Implications from a field study regarding the relationship between polycyclic aromatic hydrocarbons and glutathione S-transferase activity in mussels

An aluminium smelter on the west coast of Scotland discharges an aqueous effluent containing polycyclic aromatic hydrocarbons (PAHs) at the head of Loch Leven. The loch also supports two mussel (Mytilus edulis) farms. Data are presented on burdens of PAHs in the soft tissues of mussels and the effect of these contaminants on glutathione S-transferase (GST) activity in mussel hepatopancreas. GST activity is shown to be correlated with total PAH burden and also with the concentrations of certain individual PAHs. These field data show that high molecular weight PAHs are closely correlated to GST activity, whereas low molecular weight PAHs are not. This suggests that 5- and 6-ring PAHs have a more pronounced role than 2- to 4-ring compounds in inducing GST activity in mussels from Loch Leven. It is proposed that it may be more appropriate to link GST activity with 5- and 6-ring compounds only, rather than with the total PAH burden.     

Biological transport and mammal to mammal transfer of organochlorines in Arctic fauna

Ringed seal (Phoca hispida) is assumed to be the most important and common prey of polar bears (Ursus maritimus). However, during a scientific survey in the ice area of the northern Barents Sea east of Svalbard in June 1995, an unexpectedly high number of polar bears were observed feeding on harp seal (Phoca groenlandica) carcasses. Samples of both harp and ringed seals were obtained and organochlorine (OC) occurrence and pattern in these two potential polar bear prey species were determined. Significantly higher OC concentrations were found in harp seals, as compared to the ringed seals. All animals in the northern harp seal group were lean specimens in late moult. The industrial chemicals, polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB), and the OC pesticides bis-2,2,(chlorophenyl)-1,1,1-trichloroethanes (DDTs), hexachlorocyclohexanes (HCHs), and chlordanes (CHLORs) were analysed in blubber. The concentrations of sigma PCB (sum of concentrations of 16 PCB congeners) and sigma DDT (sum of concentrations of p,p'-DDT and p,p'-DDE) in the northern harp seal group ranged from 2093 to 20,382 and 1460 to 10,381 ng g-1 lipid weight, with mean concentrations of 11,133 and 6847 ng g-1 lipid weight, respectively. The mean concentrations of the CHLORs, oxychlordane and trans-nonachlor, were 1311 and 3743 ng g-1 lipid weight, respectively, while the mean concentrations of HCB and HCH isomers (alpha-, beta- and gamma-HCH) were all < 500 ng g-1 lipid weight. No significant difference was found in the mean total blubber mass between the two seal species when collected in June. This indicates that polar bears preying on harp seals instead of ringed seals at this time of the year could accumulate significantly higher PCB concentrations. We suggest that polar bears feeding along the ice-edge east of Svalbard in May and June preferentially prey on harp seals instead of ringed seals, and that this may partly explain the variation in PCB concentrations among polar bears from the Norwegian Arctic. An hypothesis is that the harp seal may function as a transport vector of OCs into the high Arctic environment.     

生油岩的弹性各向异性：对于油气生成和初次运移的意义

生油岩的弹性各向异性：对于油气生成和初次运移的意义ＬｅｖＶｅｒｎｉｋ等我们对来自８个沉积盆地的６９个生油岩心做了声波速度与Ｘ射线散射矿物学的各向异性实测值，Ｒｏｃｋ－Ｅｖｅｌ有机地球化孝分析，镜质体反射率和扫描电子显微镜的综合研究。速度资料表明在压实...